With all harvesting methods, however, the cotton seed, together with the fibers, always gets into the ginning plant where it is broken up into trash and seed-coat fragments. This means that ginned cotton is always contaminated with trash and dust particles and that an intensive cleaning is only possible in the spinning mill.

Nep content increases drastically with mechanical harvesting, ginning and subsequent cleaning process. The reduction of the trash content which is necessary for improving cotton grade and apperance unfortunately results in a higher nep content level.

The basic purpose of  Blow room is to supply

small fibre tufts

clean fibre tufts

homogeneously blended tufts if more than one variety of fibre is used to carding machine  without increasing  fibre rupture, fibre neps , broken seed particles and without removing more  good fibres.


The above is achieved by the following processes in the blowroom

  • Pre opening

  • pre cleaning

  • mixing or blending

  • fine opening

  • dedusting



Cleaning efficiency of the machine is the ratio of the trash removed  by the machine to that of  total trash fed to the machine, expressed as percentage

Cleaning efficieny % =(( trash in feed % - trash in del %) x 100) / (trash in feed%)


Following are the basic parameters  to be considered in Blowroom process.

  • no of opening machines

  • type of beater

  • type of beating

  • Beater speed

  • setting between feed roller and beater

  • production rate of individual machine

  • production rate of the entire line

  • thickness of the feed web

  • density of the feed web

  • fibre micronaire

  • size of the flocks in the feed

  • type of clothing  of the beater

  • point density of clothing

  • type of grid and grid settings

  • air flow through the grid

  • position of the machine in the sequence

  • amount of trash in the material

  • type of trash in the material

  • temp and relative humidity in the blow room department


Effective preopening results in smaller tuft sizes, thus creating a large surface area for easy  and efficient removal of trash particles by the fine openers.

If MBO (Rieter) or  BOW ( Trutzschler) type of machine is used as a first machine

  • the tuft size in the mixing should be as small as possible. Normally it should be less than 10 grams

  • since this machine does not take care of long term blending, mixing should be done properly to maintain the homogenous blending

  • the inclined lattice speed and the setting between inclined lattice and clearer roller decides the production of the machine

  • the setting between inclined lattice and clearer roller decides the quality of the tuft

  • if  the setting is too close, the tuft size will be small, but the neps in the cotton will be increased due to  repeated action of the  inclined lattice pins on cotton.

  • the clearance should be decided  first to confirm the quality, then inclined lattice speed can be decided according to the   production required

  • the setting of inclined lattice depends upon the fibre density, fibre micronaire and the tuft size fed. If smaller tuft is fed to the feeding conveyor, the fibre tufts will not be recycled many times, hence the neps will be less.

  • if the machine is with beater, it is advisable to use only disc type beater. Saw tooth and Pinned beaters should not be used in this machine, becasue the fibre  damage at this stage will be very high and heavier trash particles will be broken in to small pieces.

  • the beater  speed  should be around 500 to 800 rpm depending upon the rawmaterial. Coarser the fibre,  higher the speed

  • the setting between feed roller to beater should be around 4 to 7 mm

  • this machine is not meant to remove trash ,  hence the fibre loss should also be less

  • trash removal in this machine will result in breaking the seeds, which is very difficult to remove

  • It is easier to remove the bigger trash than the smaller trash, therefore enough care should be taken to avoid breaking the trash particles

  • this machine is  just to open the tufts into small sizes so that cleaning becomes easier in the next machines.

  • the fibre tuft size from this  machine should be  preferably around 100 to 200 milligrams.

  • If tuft size is  small, removing trash particles becomes easier , because of large surface area


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